evaluating performance of irrigated green space: a review of measures

Evaluating performance of irrigated green space: A review

of measures

Geoff Connellan

G&M Connellan Consultants.

With information provided by Richard Dilena, City of Greater Geelong & Peter Symes,

RBG Melbourne.

There are lots of efficiency terms.

Including Water Use Efficiency (WUE)

Ref: Irrigation Insights No 5.

Fairweather, Austin & Hope, NSW Ag. NPSI

WUE “commonly used to describe the relationship between water (input) and the

agriculture product”

WUE is an Index

WUE is used as a generic label for any performance indicators used to study water

use in “crop production”.

1. Water Use Efficiency

Measure of Landscape Outcomes delivered per unit of water input.

Strategy: Reduce plant water demand, E.g. Low water use/efficient species

2. Irrigation Efficiency

Proportion of the water applied, that is delivered into the plant root zone.

Water Use and Irrigation Efficiencies

OVERALL IRRIGATION EFFICIENCY

APPLICATION EFFICIENCY

SCHEDULING EFFICIENCY

IRRIGATION EFFICIENCY

How much water gets into the root zone ?

Efficient Delivery into

Root Zone

Aim:

High Application Efficiency

Aim: High Scheduling Efficiency

Depth and Timing matched to daily ET

ET

Factors affecting Application Efficiency

Efficiency Demands Uniformity

Assessment Individual Sprinkler Heads

1.Individual heads popped up2.Heads assessed according to the potential

fault categories:

Auditing – The Can Test

Uniformity Testing

NOTE

This discussion is based on Field or Operational performance measures.

*Scheduling Coefficients (SC)

and also

*Christiansen Coefficient (CU)

are important, particularly in terms of the design of systems.

Uniformity Testing - Calculating Field DU

DU (%) = M25 x 100 MWhere:

M - average value of all catch can readings.

M25 - average of lowest 25% of readings.

*Field DU should be greater than 75%.

Precipitation Rate (PR)

(a) Determined from a can test

also

(b) Calculated from sprinkler flow rate

Valuable data

* Validate system performance

* Determine Irrigation Schedule

Calculating Precipitation Rate

Depth

(mm)

Catch can - A very powerful performance tool!

Uniformity of ApplicationCan test readings – Volume (mL)

28 28 40 14.5 D

33 23 34 54 C

22 23.5 34 35 B

12 30 34 20 A

4 3 2 1 ROWS

Lowest:12 mL

Highest:54 mL

Uniformity Results

For example:

New irrigation systems: Field DU Should be > 75%

Existing systems: If DU < 75% System should be repaired or adjusted.

Existing systems: If DU < 60% System should be replaced.

DU as an Efficiency Measure

It is not strictly a measure of efficiency. It is an Index

Does it matter?

(1)For communication and management – No.

(2) For scientific analysis and water balance – Yes.

Soil Type Sprinkler Type

Catch CanDULQ

Soil Moisture at

12 cmDULQ

Soil Moisture at

20 cmDULQ

Sandy Loam Rotor 57% 75% 77%

Silty clay loam

Rotor 68% 86% 87%

It is the distribution of water in the soil that is important !

Comment: DU as an Efficiency Measure

Example – Low DU and High Efficiency

System with poor uniformity, application depth less that that required to refill the root zone, all the water taken up by plant roots.

It is High Efficiency! (By some measures)

RBG System Fix - Before

4.34.6

7.2

1.8 2.0

3.7

7.8

6.3

5.5

3.1

4.4

6.8

8.1

5.9

4.8

3.9

5.0

5.9

9.4

5.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

Can

1Ca

n 2

Can

3Ca

n 4

Can

5Ca

n 6

Can

7Ca

n 8

Can

9Ca

n 10

Can

11Ca

n 12

Can

13Ca

n 14

Can

15Ca

n 16

Can

17Ca

n 18

Can

19Ca

n 20

mm

Can Number

Series1

BeforeDULQ : 55% SC 25%: 1.8181% extra water required.

RBG System Fix - After

5.5

6.5

7.4

6.3

5.5

6.3

7.8 8.0

7.0

6.1

5.5

6.8

6.3

6.8 6.8

5.0

6.7

8.5

6.3 6.5

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

Can

1

Can

2

Can

3

Can

4

Can

5

Can

6

Can

7

Can

8

Can

9

Can

10

Can

11

Can

12

Can

13

Can

14

Can

15

Can

16

Can

17

Can

18

Can

19

Can

20

mm

Can Number

Series1

After DULQ 79% SC 25% 1.2626% extra water required

Measurement of Water Use

All irrigated sites need to have dedicated water meters.

.

Central control and PC based systems,

together with digital flow meters, provide comprehensive water

use data.

Reporting Water Consumption

1. Volume totals – ML

2.Trends and Reference years - % change, higher, lower

3. Application Rates (ML/ha) compared to industry standard.

* Greater exposure of Application Rates would be beneficial.

0

1

2

3

4

5

6

7

1 2 3

Series1

Water Use Reporting

Water Budget Water Used Water Required

0

1

2

3

4

5

6

7

1 2 3

Series1

Water Use Reporting

Water Budget

- Average

Water Used

- Meter

Water Required

- Actual

Inefficiency

Irrigation Index – Efficiency Indicator

The Irrigation Index (Ii)

What is: Water used relative to

Water required (volume)?

.

Reporting Water Use Performance

Irrigation Index RBG Melbourne

0

0.5

1

1.5

2

2.5

3

3.5

4

0

50000

100000

150000

200000

250000

300000

*199

3-1

994

199

4-9

5

199

5-9

6

199

6-9

7

199

7-9

8

199

8-9

9

199

9-0

0

200

0-0

1

200

1-0

2

200

2-0

3

200

3-0

4

200

4-0

5

200

5-0

6

200

6-0

7

200

7-0

8

200

8-0

9

200

9-1

0

Irri

gat

ion

Ind

ex

Kil

oli

tres

Financial Year

Irrigation AnnualMeter Total(kl)

Irrigation Index

Case Study

Reserve Irrigation Report

Richard Dilena

City of Greater Geelong

Bakers Reserve, Geelong, Jan 2012

Bakers Reserve, Geelong, Jan 2013

Bakers Reserve, Geelong, Jan 2014

Bakers Reserve Irrigation Report

Bakers Reserve Irrigation Report

Bakers Reserve Irrigation Report

Bakers Reserve Irrigation Report

Anakie Reserve Irrigation Report

Anakie Reserve Irrigation Report

Anakie Reserve Irrigation Report

Sample: Irrrigated site reportRichard Dilena, City of Greater Geelong

1 worse than crop circles v/poorIrrigation index ideal0.9 > 1.1 Visual assessment 2 crop circles poor

underwatering < 0.9 3 large degree of pattern goodoverwatering > 1.1 4 minor degree of pattern v/good

5 completely even excellent% site water budget used

ideal 0.95 to 1.05 ideal +/- 10%minor variation +/- 5% minor +/- 20%major variation +/- 10% or more major > 20%

Irrigation efficiency index -

Performance Parameters1.Irrigation index2.Irrigation efficiency3.Visual assessment4.% of water budget used

Sample: Irrrigated site reportRichard Dilena, City of Greater Geelong

SiteIrrigtaion index (Ii)

Irrigation Effi cienc

y - estimate

d (IEe)

Irrigation Effi ciency - actual

(IE)

Irrigation Effi ciency index

% of Site Water Budget

used

Visual assessme

nt

Anakie Reserve 1.01 75% 74% 0.99 95% 2Bakers Reserve 0.86 80% 93% 1.16 117% 2

Barwon Heads Village Park1.06 75% 71% 0.95 95% 3Breakwater Reserve1.17 75% 64% 0.85 102% 2

Burdoo Reserve 0.90 75% 84% 1.12 90% 5Collendina Reserve0.90 80% 89% 1.11 81% 3

Drysdale Reserve0.81 65% 82% 1.26 72% 3Elderslie Reserve0.96 75% 79% 1.05 90% 3

Flinders Peak 0.82 75% 92% 1.23 77% 2Frier Reserve 0.96 80% 83% 1.04 87% 4

Grinter Reserve 1.03 80% 78% 0.98 92% 4Grovedale Reserve0.98 80% 82% 1.03 88% 2

Hamlyn Park 1.14 80% 70% 0.88 103% 3

It is more than the water!

What is the performance of the green space?

Benefits and Value of Irrigated Green Space

(1) Social (2) Environmental(3) Economic

Physical HealthRecreation - Green Space

Active Recreation

Passive Recreation

Identifying Services or Outcomes Provided.

Example: Redleap Reserve, Whittlesea

Social Benefits: “User hours or player hours”

Services provided: AFL 11,500 Player hoursCricket 6,700 Player

hoursTotal: 18,200

Player hours

Water productivity: 3,600 player hours per ML

Exercise/Recreational Benefits Dept. Health, Vic.

Boeing Reserve, City of Moonee Valley

Stormwater development of site.

Sporting ovals, baseball, grasslands, woodlands

Health Benefits from Green Space

Physical health benefits: $400,000 (Approx.) per year

Other health benefits

•Mental health: Reduction in stress levels.

•Social benefits: Social cohesion, Liveability, Reduced rates of violence.

•Environmental benefits: Urban heat island (UHI) mitigation

Cost Benefit Analysis – Green space

Evaluated over 10 years

Community benefit: $4 million (Approx.)

Environmental benefit: $185,000 (Approx.

Costs: $3 million (Approx.)

Net benefit of green space: $0.8 million

RBG Melb. Irrigation Water Productivity

70 Litres per visitor.

What is the $ value of the benefits?

Photo: Jorge de Arujo, RBG

Efficiency Reference

CSIRO Publishing Website: http://www.publish.csiro.au/pid/5263.htm

Water Use Efficiency For Irrigated Turf and Landscape

Geoff Connellan

Summary

1.DU is a powerful measure – It describes the condition of the system and is an effective communication tool.

2. Irrigation Index (Ii) - Assesses irrigation management, scheduling and overall efficiency.

3. Precipitation rate (PR) is valuable in terms of application efficiency and also in gaining an understanding of the hydraulic performance of the system

4. Productivity measures, which assess the services of the green space, are becoming increasingly important as the value of green space is recognised.